A polar bear paparazzo brings back close-up images of these Hudson Bay celebrities.

Get a taste of what awaits you in print from this compelling excerpt.

Nosing into frigid wind (above) a polar bear sniffs for prey. About 1,200 of these majestic carnivores haunt the western edge of Canada's Hudson Bay. Here near the southernmost tip of their range, they're treading on thin ice.

Like all polar bears, those on Hudson Bay need solid ice as a platform for hunting seals and seal pups, their main prey. Yet the bay is frozen only in winter and spring, so from July to November bears must live off their fat reserves. For millennia they've coped, but climate change may be tipping the balance. "Though there's considerable variation, spring breakup is two weeks or so earlier now than it was 20 years ago," says biologist Ian Stirling of the Canadian Wildlife Service. His data show that birthrate and adult bear weight are both down about 10 percent from 1980. "If the trend continues and the ice disappears from Hudson Bay," says University of Alberta biologist Andrew Derocher, "it's pretty clear that these bears will disappear too."

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Even at subzero temperatures, polar bears retain virtually all their body heat. Two layers of fur and thick fat act as superb insulation.

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A dozing bear won't lie for long as autumn blizzards hit. Snow, cold, and the promise of food will lure him toward Hudson Bay to stalk the winter ice. With ice tending to melt earlier in the spring, the winter hunt grows urgent.

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

Vicks VapoRub, the pungent ointment that helps some of us breathe easier when we have colds, may now help young orphan polar bear cubs survive in the wild. Adult polar bears have an acute sense of smell, and a mother bear can easily detect that an orphaned cub is not her own. She will have nothing to do with the young bear; that cub, who needs to nurse until it is about two years old, will be left with the near impossible task of fending for itself. In the past when an orphaned cub found its way to Churchill, Manitoba, on the western edge of Hudson Bay, the government would have to place it in a zoo or euthanize it. Recently, though, researchers funded by Britain's Born Free Foundation have been taking orphans and suitable foster mothers (ideally with a cub of their own), rubbing their faces, necks, and backs with VapoRub, and airlifting them by helicopter to a remote release site. Will the VapoRub mask an orphan's smell enough that an adult female bear will be fooled into thinking the cub is her own? Will she take on the role of surrogate mother? The technique appears to have been successful in at least half the cases.

Abby Tipton

Polar Bear Central www.wwfcanada.org/en/PolarBearCentral/default.aspWant to adopt a polar bear? This World Wildlife FundCanada website, designed for kids, gives you a chance to do just that and to learn about the behavior, habitat, and natural history of Ursus maritimus.

Churchill Northern Studies Centrewww.churchillmb.net/~cnsc/A research and educational facility in Churchill, Manitoba, CNSC offers courses and adventure study tours that are intended to promote an understanding of polar bears and other wildlife of the region.

Space for Specieswww.spaceforspecies.caBring science to life. Log on to this Web-based learning program and monitor the travels of individual polar bears through satellite telemetry. Download a tracking journal and plot your bear's movements, record weather data, note changes in habitat, and chat with experts.

Polar Bears Internationalwww.polarbearsalive.orgThis website sponsored by a nonprofit group dedicated to the conservation of polar bears provides a wealth of information on the natural history of, threats to, and research on polar bears. It even has a video camera that broadcasts live from Hudson Bay so you can sign up and watch the bears in real time.